This invention relates to an elongate composite article for treating molten iron for altering same.
One process for treating molten iron for altering same includes enclosing powered treating agents within a relatively thick-walled metal conduit thereby forming a wire-like article which is inserted into the molten iron at a preselected controlled feed rate. The molten iron dissolves the conduit thereby releasing the treating agent into the molten iron. The conduit is commonly made of steel since steel is highly ductile and does not alter the composition of the molten iron to any significant degree. The wire-like article is normally made by depositing a metered amount of treating agent onto a steel strip, rolling the strip into a tube and enclosing the treating agent, and then drawing the tube down to a smaller size to compact the treating agent and reduce the wall thickness of the tube.
One of the problems encountered with that process of treating molten iron is that the melting point of the steel conduit is higher than the normal pour temperature of the molten iron and the steel conduit is dissolved by the combinations of a solid state diffusion and melting reaction. The time required to dissolve through the relatively thick-walled conduit undesirably delays the final dissolution of the article in the molten iron and also undesirably limits the maximum permissible feed rate of the article into the molten iron.
It is not practical to make the conduit from a cast iron or similar composition of the melt because the ductility of cast iron is low as compared to a low carbon steel. Therefore, a cast iron strip cannot feasibly be rolled into a conduit. Moreover, the use of a conduit having a relatively thin steel wall is not practical since the process commonly used to make the wire-like article leaves a seam. With a thin walled conduit, the seam has a tendency to split open thereby allowing the treating agent to spill out when the article is coiled unto a reel.